Optimization of cranial nerve stimulation to treat seizure disorders during sleep

ABSTRACT

A method includes determining sleep cycle information related to a sleep cycle of a patient based on body parameter data. The method also includes adjusting a cranial nerve stimulation parameter based on the sleep cycle information.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 13/834,523, filed Mar. 15, 2013, pending, thepriority of which is claimed and the disclosure of which is incorporatedby reference in its entirety.

FIELD OF THE DISCLOSURE

The present disclosure is generally related to cranial nerve stimulationto treat seizure disorders

BACKGROUND

Sleep may be characterized by four stages, stage one sleep, stage twosleep, stage three sleep, and rapid eye movements (REM) stage sleep. Thefour stages may form a sleep cycle. Typically in a sleep cycle, a personexperiences the four stages in sequence (e.g., stage one sleep→stage twosleep→stage three sleep→REM stage sleep). A person may experienceseveral sleep cycles during a sleep period (e.g., during a night). Thenumber of sleep cycles a person experiences per sleep period depends onthe age of the person, duration of the sleep period, and other factors.

Neurological disorders (e.g., a seizure disorder or depression) mayinterfere with a person's sleep quality. For example, a patient with aseizure disorder may experience seizures during sleep. The seizuresexperienced during sleep may affect the patient's sleep quality. Whenthe patient has a seizure during sleep, the seizure may awaken thepatient prematurely from a particular sleep cycle. The patient does notfinish the particular sleep cycle and has to fall back asleep to startanother sleep cycle. Thus, the patient experiences sleep deprivation.

SUMMARY

Seizures that occur during sleep may deprive a patient of sleep. In somepatients, seizures are more common during stage 2 sleep. When a patientexperiences a seizure during stage 2 sleep, instead of transitioning tostage 3 sleep, the seizure may awaken the patient. Thus, the patient maynot get an appropriate amount of stage 3 sleep and/or REM stage sleepand may experience sleep deprivation. When the patient goes back tosleep, the patient may start from stage 1 sleep of a new sleep cycle ormay stay in stage 3 sleep without transitioning to REM stage sleep.Sleep deprivation may have negative physiological effects on thepatient, such as memory impairment, mental impairment, etc.

Systems and methods described herein may improve sleep quality of apatient with a seizure disorder. For example, an implantable medicaldevice (IMD) may determine sleep cycle information related to one ormore sleep cycles of a patient by monitoring body parameter data of thepatient. The sleep cycle information may include a particular sleepstage, a sleep stage transition, an amount of time the patient spends inone or more sleep stages during a sleep cycle and/or multiple sleepcycles, or a combination thereof. Based on the sleep cycle information,the IMD may apply cranial nerve stimulation (CNS) to the patient to helpthe patient complete the four stages of a sleep cycle. The IMD may also,or in the alternative, adjust one or more CNS parameters based on thesleep cycle information to treat one or more seizure disorders. CNS mayinclude vagus nerve stimulation (VNS), trigeminal nerve stimulation(TNS), stimulation of other cranial nerves, or a combination thereof.

To illustrate, the IMD may determine a sleep stage of the patient andmay monitor sleep stage transitions. Empirical data has shown thatseizures may occur more frequently and may be more severe during stage 2sleep and may occur less frequently during stage 3 sleep and REM stagesleep. When the IMD determines that the patient is in stage 2 sleep, theIMD may adjust a CNS parameter to drive the patient toward stage 3 sleepand subsequently toward REM stage sleep to complete a sleep cycle. Whenthe patient reaches stage 3 sleep and/or REM stage sleep of a sleepcycle, the likelihood of a seizure occurring during the sleep cycle maybe reduced. The patient may get an increased amount of sleep in eachsleep cycle as compared to an amount of sleep of a patient awakened byseizures. Thus, the patient may have improved sleep quality and may alsoexperience fewer seizures during sleep.

The IMD may also, or in the alternative, determine information regardingefficacy of a CNS therapy based on the sleep cycle information. Forexample, the IMD or an external device (e.g., a computing device) maycompare sleep cycle information of the patient before applying CNStherapy to sleep cycle information of the patient during and/or afterthe CNS therapy. One or more CNS parameters of the CNS therapy may beadjusted based on the comparison to increase the efficacy of the CNStherapy.

In a particular embodiment, a method includes determining sleep cycleinformation related to a sleep cycle of a patient based on bodyparameter data. The method also includes adjusting a cranial nervestimulation parameter based on the sleep cycle information.

In another particular embodiment, a device includes a processor that isconfigured to determine sleep cycle information related to a sleep cycleof a patient based on body parameter data. The processor is furtherconfigured to adjust a cranial nerve stimulation parameter based on thesleep cycle information. The apparatus also includes a memory coupled tothe processor. The apparatus further includes a therapy delivery unitconfigured to apply cranial nerve stimulation based on the sleep cycleinformation.

In another particular embodiment, a non-transitory computer-readablemedium includes instructions executable by a processor. The instructionsmay be executable by the processor to determine sleep cycle informationrelated to a sleep cycle of a patient based on body parameter data andto adjust a cranial nerve stimulation parameter based on the sleep cycleinformation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a particular embodiment of a system thatuses cranial nerve stimulation to treat seizures during sleep;

FIG. 2A is a diagram illustrating a sleep pattern when no seizures occurduring sleep;

FIG. 2B is a diagram illustrating a sleep pattern when seizures occurduring sleep;

FIG. 3 is a diagram illustrating an effect of cranial nerve stimulationin a sleep stage;

FIG. 4 is a diagram illustrating cranial nerve stimulation parameteradjustments based on sleep cycle information;

FIG. 5A is a diagram of a sleep quota of a patient before receivingcranial nerve stimulation;

FIG. 5B is a diagram of a sleep quota of the patient of FIG. 5A afterreceiving cranial nerve stimulation;

FIG. 6 is a flow chart of a first particular embodiment of a method ofoperation of a medical device associated with a cranial nervestimulation therapy to treat seizures during sleep;

FIG. 7 is a flow chart of a second particular embodiment of a method ofoperation of a medical device associated with a cranial nervestimulation therapy to treat seizures during sleep; and

FIG. 8 is a flow chart of a third particular embodiment of a method ofoperation of a medical device associated with a cranial nervestimulation therapy to treat seizures during sleep.

DETAILED DESCRIPTION

Referring to FIG. 1, a block diagram of a system 100 that uses cranialnerve stimulation (CNS) to treat seizures of a patient 102 (e.g., anepilepsy patient) during sleep is shown according an exemplaryembodiment. CNS may include vagus nerve stimulation (VNS), trigeminalnerve stimulation (TNS), stimulation of other cranial nerves, or acombination thereof. The system 100 may include an implantable medicaldevice (IMD) 104, a sensor data collection system 106, and/or anexternal programming device 108. The IMD 104 may include a processor110, a memory 112, a data gathering unit (DGU) 114, a therapy deliveryunit (TDU) 116, a power unit (PU) 118, a transceiver (TX) 120, a systembus 124, other components (not shown), or a combination thereof. Theprocessor 110 may be a single processor of the IMD 104 or multipleprocessors of the IMD 104. The memory 112 may include instructions 122that are executable by the processor 110 to perform or control variousfunctions of the IMD 104.

The data gathering unit 114 may gather data related to an operationalstate of the IMD 104 (e.g., a charge state of the power unit 118), datarelated to therapy provided to the patient 102, body parameter datacorresponding to one or more body parameters of the patient 102, or acombination thereof. Data gathered by the data gathering unit 114 may beused to control therapy provided to the patient 102, may be transmittedto an external device, may be stored in the memory 112, transmitted to aserver (e.g., a cloud), or a combination thereof.

The therapy delivery unit 116 may be configured to provide therapy tothe patient 102. For example, the therapy delivery unit 116 may provideelectrical stimulation (via one or more electrodes (not shown)) totissue of the patient 102. The therapy delivery unit 116 may provideelectrical stimulation to a cranial nerve (e.g., the vagus nerve, thetrigeminal nerve, etc.) of the patient 102. As another example, thetherapy delivery unit 116 may include a drug pump that delivers a drugor drugs to the patient 102. Therapy provided by the therapy deliveryunit 116 may be controlled by the processor 110 based on a treatmentprogram.

The power unit 118 may provide electrical power to components of the IMD104. For example, the power unit 118 may include a battery or acapacitor. The transceiver 120 may enable the IMD 104 to communicatewith other devices, such as the sensor data collection system 106 andthe external programming device 108. The processor 110, the memory 112,the data gathering unit 114, the therapy delivery unit 116, the powerstorage unit 118, the transceiver 120, other components of the IMD 104,or a combination thereof, may be connected via the system bus 124.

The sensor data collection system 106 may include a processor 126, amemory 128, a sensor data gathering unit (SDGU) 130, a power unit (PU)132, a transceiver (TX) 134, a system bus 138, other components (notshown), or a combination thereof. The processor 126 may be a singleprocessor of the sensor data collection system 106 or multipleprocessors of the sensor data collection system 106. The memory 128 mayinclude instructions 136 that are executable by the processor 126 toperform or control various functions of the sensor data collectionsystem 106.

The sensor data gathering unit 130 may be configured to collect bodyparameter data from sensors placed on or implanted within tissue of thepatient 102. For example, an electroencephalography (EEG) sensor 140, anelectrooculography (EOG) sensor 142, an electrocardiography (ECG) sensor144, an electromyography (EMG) sensor 146, an accelerometer 148, animpedance monitoring unit, a respiration sensor (e.g., on the chest ornose), a blood oxygenation sensor, an acoustic sensor (e.g., to measuresnoring), other sensors, or a combination thereof, may be placed on orimplanted within tissue of the patient 102 to sense the body parameterdata of the patient 102. The body parameter data may include EEG data,EOG data, ECG data, EMG data, accelerometer data, or a combinationthereof. The sensor data gathering unit 130 may receive the bodyparameter data via respective wired or wireless connections to the EEGsensor 140, the EOG sensor 142, the ECG sensor 144, the EMG sensor 146,the accelerometer 148, the other sensors, or a combination thereof.

The power unit 132 may be configured to provide electrical power tocomponents of the sensor data collection system 106. For example, thepower unit 132 may include a battery, a capacitor, a power supplycoupled to an external source (e.g., alternate current (AC) power), or acombination thereof. The power unit 132 may be configured to selectivelypower on and off one or more of the various sensors on demand. Thetransceiver 134 may be configured to enable the sensor data collectionsystem 106 to communicate with other devices, such as the IMD 104, theexternal programming device 108, or both. The processor 126, the memory128, the sensor data gathering unit 130, the power unit 132, and thetransceiver 134 may be connected via the system bus 138.

The external programming device 108 may include a transceiver (TX) 150and an antenna 152. The transceiver 150 may be configured to communicate(e.g., transmit data, receive data, or a combination thereof) via theantenna 152 with the IMD 104, the sensor data collection system 106, orboth. For example, the external programming device 108 may send programdata, such as therapy parameter data to the IMD 104 using wirelesssignals. The program data may be stored at a memory 154 of the externalprogramming device 108, may be received from an external computingdevice 160, or both. In a particular embodiment, the externalprogramming device 108 may also include a processor 156 and/or acommunication interface 158 to communicate with the external computingdevice 160.

The external computing device 160 may include a processor 162, a memory164, a communication interface 166, a display 168, other components (notshown), or a combination thereof. The external computing device 160 mayreceive data from the external programming device 108, the sensor datacollection system 106, the IMD 104, or a combination thereof, via thecommunication interface 166 and may store the data in the memory 164.The external computing device 160 may provide an interface (e.g., viathe display 168) to the patient 102 and/or a health care provider to seethe stored data. The stored data may be used to facilitate determininginformation regarding efficacy of a therapy.

During operation, when the patient 102 is asleep, the sensor datacollection system 106 may collect the body parameter data from the EEGsensor 140, the EOG sensor 142, the ECG sensor 144, the EMG sensor 146,the accelerometer 148, another sensor, or a combination thereof. Thesensor data collection system 106 may communicate the body parameterdata to the IMD 104 occasionally (e.g., periodically or in response todetection of an event) or continuously. For example, the sensor datacollection system 106 may communicate the body parameter data to the IMD104 in real time (as soon as the sensor data collection system 106receives the body parameter data and processes the body parameter datafor transmission). Based on the body parameter data, the IMD 104, thesensor data collection system 106, the external programming device 108,the external computing device 160, or a combination thereof, maydetermine sleep cycle information related to a sleep cycle of thepatient 102.

The IMD 104, the sensor data collection system 106, the externalprogramming device 108, the external computing device 160, or acombination thereof, may evaluate the sleep cycle information todetermine a sleep stage (e.g., stage 1 sleep, stage 2 sleep, stage 3sleep, and/or REM stage sleep) of the patient 102. The IMD 104, thesensor data collection system 106, the external programming device 108,the external computing device 160, or a combination thereof, may also,or in the alternative, evaluate the sleep cycle information to detect asleep stage transition. For example, the sleep stage transition mayinclude a transition from stage 1 sleep to stage 2 sleep, a transitionfrom stage 2 sleep to stage 3 sleep, a transition from stage 3 sleep toREM stage sleep, a transition from REM stage sleep to stage 1 sleep, atransition from one of stage 1 sleep, stage 2 sleep, stage 3 sleep,and/or REM stage sleep to wakefulness, or a combination thereof.

The IMD 104, the sensor data collection system 106, the externalprogramming device 108, the external computing device 160, or acombination thereof, may also, or in the alternative, evaluate the sleepcycle information to determine an amount of time the patient 102 spendsin one or more sleep stages during a sleep cycle (e.g., a sleep quota).The IMD 104, the sensor data collection system 106, the externalprogramming device 108, the external computing device 160, or acombination thereof, may also, or in the alternative, evaluate the sleepcycle information to determine an amount of time the patient 102 hasspent in one or more sleeps stages during a sleep period. The sleepperiod may include multiple sleep cycles. For example, based on bodyparameter data, the IMD 104, the sensor data collection system 106, theexternal programming device 108, the external computing device 160, or acombination thereof, may monitor the sleep quota and/or the amount oftime the patient 102 has spent in one or more sleep stages during thesleep period.

Based on the sleep cycle information, the IMD 104, the sensor datacollection system 106, the external programming device 108, the externalcomputing device 160, or a combination thereof, may adjust one or moreCNS parameters to adjust the CNS applied to the patient 102. The one ormore CNS parameters may include a pulse width, an output current, anoutput voltage, a pulse frequency, a burst frequency, an interburstinterval, a duty cycle, an on-time, an off-time, a frequency sweep, or acombination thereof. The one or more CNS parameters may be used togenerate stimulation signals applied to a cranial nerve of the patient102. For example, when the sleep cycle information indicates atransition from stage 2 sleep toward wakefulness (e.g., a transitionfrom stage 2 sleep toward wakefulness caused by a seizure), the IMD 104may adjust the CNS parameter such that synchrony of brainwaves of thepatient 102 is increased so that the CNS may drive the patient towardstage 3. In some embodiments, the IMD 104 may adjust the CNS parametersuch that the CNS may drive the patient 102 toward stage 3 sleep whenthe sleep cycle information indicates a transition from stage 1 sleep tostage 2 sleep, a current sleep stage is stage 2 sleep, a predeterminedamount of time has been spent in stage 2 sleep during a sleep cycle, ora combination thereof. Applying CNS to drive the patient 102 towardstage 3 sleep to continue the sleep cycle may reduce seizures asempirical data has shown that seizures rarely occur in stage 3 sleep orREM stage sleep. Furthermore, the patient 102 may have improved sleepquality as the patient 102 continues to sleep instead of waking up.Adjusting the CNS parameter such that synchrony of the brainwaves of thepatient 102 is either increased or decreased is described in more detailwith reference to FIG. 4.

As another example, when the sleep cycle information indicates that anamount of time the patient 102 has spent in REM stage sleep during asleep period is less than a first threshold, the IMD 104 may adjust theCNS parameter such that the CNS may drive the patient 102 toward REMstage sleep (e.g., remaining in REM stage sleep until the patient 102has spent an amount of time in REM stage sleep equal to the threshold).

As another example, when the sleep cycle information indicates that anamount of time the patient 102 has spent in stage 3 sleep during a sleepperiod is less than a second threshold, the IMD 104 may adjust the CNSparameter such that the CNS may drive the patient 102 toward stage 3sleep (e.g., remaining in stage 3 sleep until the patient 102 has spentan amount of time in stage 3 sleep equal to the second threshold). Anamount of time the patient 102 spent in stage 1 sleep may also becompared to a third threshold. An amount of time the patient 102 spentin stage 2 sleep may be compared to a fourth threshold. The first,second, third, and fourth thresholds may correspond to an amount oftime, or a portion thereof, that a healthy person may spend in REM stagesleep, stage 3 sleep, stage 1 sleep, and stage 2 sleep, respectively.

Transitions from one sleep stage to another sleep stage may beidentified by distinct characteristics associated with each stage of asleep cycle. For example, stage 1 sleep may be identified based on thepresence of hypnic jerks (e.g., involuntary twitching of muscles). Theaccelerometer 148 may be placed on a limp of the patient 102 to detectbody movements associated with hypnic jerks. The sensor data collectionsystem 106 may collect the accelerometer data from the accelerometer148. The IMD 104 and/or the sensor data collection system 106 mayanalyze the accelerometer data to determine whether the patient 102 isin stage 1 sleep or has transitioned into stage 1 sleep. A firstparticular number of occurrences of the hypnic jerks (e.g., a thresholdnumber during a particular time period) may indicate that the patient102 has transitioned from wakefulness to stage 1 sleep. Consistentoccurrences of hypnic jerks may indicate that the patient 102 is instage 1 sleep.

Stage 2 sleep may be identified based on a decrease in body movements(e.g., a decrease in frequency of body movements, a decrease infrequency of hypnic jerks, and/or absence of hypnic jerks) relative tothe body movements in stage 1 sleep, the presence of sleep spindles(e.g., bursts of oscillatory brain activities with frequenciesapproximately between 12 Hz to 14 Hz and a duration of approximately atleast 0.5 second), and/or the presence of relatively stable heart rates.The decrease in body movements may be identified from the accelerometerdata and/or EMG data. The EMG sensor 146 may be placed on the torso ofthe patient 102. Because the presence of hypnic jerks may indicate thatthe patient 102 is in stage 1 sleep, a period of no registered bodymovements or a decrease in frequency of body movements following thepresence of hypnic jerks may indicate that the patient 102 hastransitioned from stage 1 sleep to stage 2 sleep. Snoring may also be anindicator of stage 2 sleep which can be measured by either anaccelerometer signal, respiration sensor placed on the torso or on thenose, an impedance monitoring unit, or a combination thereof.

In addition or alternatively, the EEG sensor 140 may be placed on thehead of the patient 102 to detect brain electrical activity of thepatient 102. The IMD 104 and/or the sensor data collection system 106may analyze the EEG data (e.g., the brain electrical activities thepatient 102) to determine whether the patient 102 is in stage 2 sleep orhas transitioned into stage 2 sleep based on the presence of sleepspindles. A first particular number of occurrences of the sleep spindlesmay indicate that the patient 102 has transitioned from stage 1 sleep tostage 2 sleep. Consistent occurrences of the sleep spindles may indicatethat the patient 102 is in stage 2 sleep.

In addition or alternatively, the ECG sensor 144 may be placed on thetorso of the patient 102 (e.g., near the chest of the patient 102) todetect electrical activities of the heart of the patient 102. The IMD104 and/or the sensor data collection system 106 may analyze the ECGdata (e.g., the electrical activities of the heart of the patient 102)to determine whether the patient 102 is in stage 2 sleep or hastransitioned into stage 2 sleep. A first particular number ofoccurrences of orderly ECG patterns (e.g., a threshold number during aparticular duration) may indicate that the patient 102 has transitionedfrom stage 1 sleep to stage 2 sleep. Consistent occurrences of theorderly ECG patterns may indicate that the patient 102 is in stage 2sleep. Stage 1 sleep and stage 2 sleep are considered light sleepstages.

Stage 3 sleep may be identified based on an increase in body movementsrelative to the body movements of the patient 102 in stage 2 sleepand/or a decrease in frequency of electrical activities of the brain ofthe patient 102. The IMD 104 and/or the sensor data collection system106 may analyze the accelerometer data, the EMG data, and/or the EEGdata to determine whether the patient 102 is in stage 3 sleep. Theincrease in body movements may be identified using the accelerometerdata and/or the EMG data. A first particular number of occurrences ofincreased body movements (e.g., a threshold number during a particularduration) may indicate that the patient 102 has transitioned from stage2 sleep to stage 3 sleep. Consistent occurrences of the increased bodymovements relative to the body movements in stage 2 sleep may indicatethat the patient 102 is in stage 3 sleep. A first particular number ofoccurrences of brain electrical activities with a decreased frequencyrelative to the frequency of brain electrical activities in stage 2sleep (e.g., 0.5 Hz-2 Hz in stage 3 sleep as compared to 12 Hz-14 Hz instage 2 sleep) may indicate that the patient 102 has transitioned fromstage 2 sleep to stage 3 sleep. Consistent occurrences of brainelectrical activities with a decreased frequency relative to thefrequency of brain electrical activities in stage 2 sleep may indicatethat the patient 102 is in stage 3 sleep. Also, a decrease in snoringfrom stage 2 sleep may be an indicator of stage 3 sleep. Stage 3 sleepis considered a deep sleep stage.

REM stage sleep may be identified based on an increase in eye movementsof the patient 102 relative to the eye movements of the patient 102 instage 3 and/or a decrease in body movements of the patient 102 relativeto the body movements of the patient 102 in stage 3. The EOG sensor 142may be placed near the eyes of the patient 102 to detect the eyemovements of the patient 102. The IMD 104 and/or the sensor datacollection system 106 may analyze the EOG data and/or the accelerometerdata to determine whether the patient 102 is in REM stage sleep. A firstparticular number of occurrences of eye movements with an increasedfrequency relative to the eye movements in stage 3 (e.g., a thresholdnumber during a particular duration) may indicate that the patient 102has transitioned from stage 3 sleep to REM stage sleep. Consistentoccurrences of eye movements with an increased frequency relative to thefrequency of the eye movements in stage 3 sleep may indicate that thepatient 102 is in REM stage sleep. In addition, a decrease in snoringfrom stage 3 sleep, or the absence of snoring may be an indicator of REMstage sleep. Generally, snoring is more prominent in the light sleepstages (e.g., stage 1 sleep and stage 2 sleep), decreases during deepsleep (e.g., stage 3 sleep), and further decreases and may be absentduring REM stage sleep. Exceptions to this snoring pattern may apply topatients with certain disorders (e.g., sleep apnea).

When the patient 102 transitions from a sleep stage to wakefulness, sucha transition may be detected based on an increase in heart rate relativeto a heart rate of the patient 102 in the sleep stage via the ECG data,an increase in a frequency of the brain electrical activities relativeto a frequency of the brain electrical activities of the patient 102 inthe sleep stage via the EEG data, and an increase in body movementrelative to the body movements of the patient 102 in the sleep stage viathe accelerometer data, the EMG data, or a combination thereof. Sleepstage determination sensitivity and specificity may be increased byusing multiple sensors. For example, the combination of ECG, EEG, andaccelerometer may provide a more accurate indication of a current sleepstage that any one of those sensor types alone.

In a particular embodiment, the sensor data collection system 106determines the sleep cycle information based on the body parameter dataand also determines CNS adjustment data based on the sleep cycleinformation. The sensor data collection system 106 transmits the CNSadjustment data to the IMD 104. The IMD 104 adjusts one or more CNSparameters based on the CNS adjustment data. In a particular embodiment,the IMD 104 or the sensor data collection system 106 determines anefficacy of a CNS therapy based on a comparison of sleep cycleinformation of the patient 102 before a CNS therapy and sleep cycleinformation of the patient 102 during and/or after the CNS therapy. Forexample, the IMD 104 or the sensor data collection system 106 maycompare a first sleep quota of the patient 102 before a CNS therapy to asecond sleep quota of the patient 102 after the CNS therapy. As anotherexample, the IMD 104 or the sensor data collection system 106 maycompare the second sleep quota to a threshold. The system 100 mayimprove sleep quality of the patient 102 and may reduce seizures thatthe patient 102 experiences during sleep.

In addition to adjusting CNS parameters based on sleep cycleinformation, a seizure detection algorithm may be adjusted based on thesleep cycle information. One or more parameters of a seizure detectionalgorithm may be adjusted based on a current sleep stage, sleep stagetransition, an amount of time spent in a particular sleep stage,probability of a seizure occurring in a current stage, a patient's sleephistory, other sleep cycle information, or a combination thereof. Insome embodiments, the one or more parameters of the seizure detectionalgorithm may be adjusted to increase seizure detection sensitivity whenthe current sleep stage is stage 2 sleep, as a seizure is more likely tooccur in stage 2 sleep than in stage 3 sleep and REM stage sleep.Certain parameters may be adjusted to be more sensitive while others maybe adjusted to be less sensitive depending on the sleep stage. Forexample, the seizure detection algorithm may adjust detection parametersassociated with the accelerometer to distinguish hypnic jerks from aseizure. The seizure detection algorithm may be adjusted to be lesssensitive to the accelerometer during stage 1 sleep or additionalprocessing of the accelerometer signal may be used to furtherdistinguish, and filter out, hypnic jerks from movements characteristicof a seizure.

Referring to FIG. 2A, a diagram illustrating a sleep pattern 200 of apatient (e.g., the patient 102 of FIG. 1) when no seizures occur duringsleep is shown according to an exemplary embodiment. The sleep pattern200 may include a first sleep cycle 202, a second sleep cycle 204, and athird sleep cycle 206. During the first sleep cycle 202, the patient 102may spend a first amount of time 208 in stage 3 sleep and may spend asecond amount of time 210 in REM stage sleep. During the second sleepcycle 204, the patient 102 may spend a third amount of time 212 in stage3 sleep and may spend a fourth amount of time 214 in REM stage sleep.The first amount of time 208 is typically a longer duration of time thanthe third amount of time 212. The second amount of time 210 is typicallya shorter duration of time than the fourth amount of time 214. Duringthe third sleep cycle 206, the patient 102 may spend a fifth amount oftime 216 in stage 3 sleep and may spend a sixth amount of time 218 inREM stage sleep. The third amount of time 212 is typically a longerduration of time than the fifth amount of time 216. The fourth amount oftime 214 is typically a shorter duration of time than the sixth amountof time 218. The sleep pattern 200 may illustrate that an amount of timespent in stage 3 sleep decreases as the patient 102 gets closer tocompleting a sleep period. The sleep pattern 200 may also illustratethat an amount of time spent in REM stage sleep increases as the patient102 gets close to completing the sleep period.

FIG. 2A, also illustrates a diagram of a sleep pattern 220 of thepatient 102 when seizures occur during sleep is shown according to anexemplary embodiment. The sleep pattern 220 may include a fourth sleepcycle 222, a fifth sleep cycle 224, and a sixth sleep cycle 226. Duringthe fourth sleep cycle 222, the patient 102 experiences a first seizure228 during stage 2 sleep and the patient 102 is awakened by the firstseizure 228. Because the patient 102 is awakened before transitioning tostage 3 sleep, the patient 102 may not get any stage 3 sleep or REMstage sleep during the fourth sleep cycle 222. During the fifth sleepcycle 224, the patient 102 experiences a second seizure 230 during stage2 sleep and the patient 102 is awakened by the second seizure 230.Because the patient 102 is awakened before transitioning to stage 3sleep, the patient 102 may not get any stage 3 sleep or REM stage sleepduring the fifth sleep cycle 24. During the sixth sleep cycle 226, thepatient 102 may go directly into stage 3 sleep to compensate for thelack of stage 3 sleep, but may not get any stage 1, stage 2, and REMstage sleep. The sleep pattern 220 illustrates that seizures that occurduring sleep may interfere with the sleep quality of the patient 102.

Referring to FIG. 2B, a diagram illustrating a sleep pattern 240 of thepatient 102 when no seizures occur during sleep is shown according to anexemplary embodiment. The sleep pattern 240 may include a seventh sleepcycle 242, an eighth sleep cycle 244, and a ninth sleep cycle 246.During the seventh sleep cycle 242 in stage 2 sleep 248 the patient 102begins to vacillate at 252 between stage 2 sleep 248 and stage 3 sleep250 never fully entering or remaining in stage 3 sleep 250 and thentransitions to an awake state. During the eighth sleep cycle 244 thepatient 102 again begins to vacillate at 254 between stage 2 sleep 248and stage 3 sleep 250 never fully entering or remaining in stage 3 sleep250 and then transitions to an awake state. During the ninth sleep cycle246, the patient 102 successfully transitions from stage 2 sleep 248 tostage 3 sleep 250 and spends a fourth amount of time 256 in stage 3sleep. However, the patient may then transition to an awake state beforeentering REM stage sleep. In this sleep pattern 240 the patient 102 getslittle deep restorative stage 3 sleep only spending a fourth amount oftime 256 in stage 3 sleep, and no REM sleep. In FIG. 2B, a sleep pattern260 is illustrated having the same seventh sleep cycle 242, eighth sleepcycle 244, and stage 1 through 3 sleep of the ninth sleep cycle 246 assleep pattern 240. In sleep pattern 260, the patient transitions to REMstage sleep in the ninth sleep cycle 246 and spends a fifth amount oftime 264 in REM stage sleep and begins a tenth sleep cycle 262. In thissleep pattern 260 the patient 102 gets little deep restorative stage 3sleep only spending a fourth amount of time 256 in stage 3 sleep, andlittle REM sleep spending only a fifth amount of time 264 on REM stagesleep.

Patients with neurological disorders, including epilepsy, often exhibitpoor sleep architecture. Patients with epilepsy may experience periodsin which their brain state is unstable, but does not arise to the levelof a seizure. During sleep, these unstable periods may be more likely tooccur during stage 2 sleep or the transition from stage 2 sleep to stage3 sleep. In the unstable brain state, the patient may vacillate betweenstage 2 sleep and stage 3 sleep followed by an awake state. The lack ofdeep restorative stage 3 sleep and REM sleep may result in sleepdeprivation and may aggravate or worsen the patient's epilepsy or otherneurological condition.

Referring to FIG. 3, diagrams illustrating an effect of cranial nervestimulation in a sleep stage are shown according to an exemplaryembodiment. In diagram 300, line 302 represents an amount of time apatient (e.g., the patient 102 of FIG. 1) has spent in stage 2 sleep ina particular sleep cycle (e.g., as monitored by the IMD 104 of FIG. 1 orthe sensor data collection system 106). In diagram 300, CNS may beadjusted and applied to help drive the patient toward stage 3 sleep whenthe sleep cycle information indicates a transition to stage 2 sleep at304, a current sleep stage is stage 2 sleep, a predetermined amount oftime 306 spent in stage 2 sleep during a sleep cycle, or a combinationthereof. In some embodiments, a seizure or otherwise unstable brainstate may be avoided by assisting the patient through stage 2 sleep tostage 3 sleep.

As illustrated in diagram 320, line 322 represents a patient's stage 2sleep being interrupted by a seizure or an unstable brain state at 324.The patient may start transitioning at, or near, 324 from stage 2 sleeptoward an awake state instead of remaining in stage 2 sleep.

In diagram 340, line 342 represents a patient's stage 2 sleep beginningto transition toward an awake state at 344 resulting from the onset of aseizure or an unstable brain state. Based on the sleep cycleinformation, the IMD 104 of FIG. 1 may identify the transition fromstage 2 sleep toward wakefulness. In response to identifying thetransition, the IMD 104 may adjust one or more CNS parameters to adjustthe CNS applied to the patient 102 or may start applying CNS accordingto the adjusted one or more CNS parameters, at 346. The CNS may drivethe patient 102 toward stage 3 sleep (e.g., remain in stage 2 sleepuntil the patient 102 has spent an amount of time in stage 2 sleep equalto the threshold 302). In response to receiving the CNS appliedaccording to the one or more adjusted parameters, the patient 102 mayremain or return to stage 2 sleep at 348 and continue toward stage 3sleep.

Referring to FIG. 4, a diagram 400 illustrating, in a simplified form,brain wave synchrony over time in various sleep stages is shownaccording to an exemplary embodiment. The diagram 400 may be a synchronyprofile. The synchrony profile may indicate synchrony level changes ineach sleep stage as measured by different EEG channels (e.g., differentEEG probes) when no seizures occur during sleep. The diagram 400 mayinclude a first segment 404, a second segment 406, a third segment 408,and a fourth segment 410. Synchrony of the brain waves may includesynchrony of brain wave frequency as measured by the different EEGchannels, synchrony of brain wave energy as measured by the differentEEG channels, synchrony of brain wave stability as measured by thedifferent EEG channels, synchrony of brain wave phase as measured by thedifferent EEG channel, or a combination thereof. In addition, the changein synchrony of brain waves may also be measured within and/or acrossmultiple EEG channels. Furthermore, the change in synchrony withinand/or across multiple channels of different body parameters may also bemeasured.

As shown in FIG. 4, when a patient (e.g., the patient 102 of FIG. 1) isin stage 1 sleep, a synchrony of the brain waves may increase (i.e.,become more synchronous) relative to a synchrony of the brain waves whenthe patient is awake, as indicated by the first segment 404. When thepatient is in stage 2 sleep, a synchrony of the brain waves mayfluctuate as indicated by the second segment 406. When the patient is instage 3 sleep, a synchrony of the brain waves may increase relative tothe synchrony of the brain waves in stage 2 sleep, as indicated by thethird segment 408. When the patient is in REM stage sleep, a synchronyof the brain waves may decrease (i.e., become less synchronous) relativeto the synchrony of the brain waves in stage 3 sleep, as indicated bythe fourth segment 410.

In FIG. 4, a diagram 420 illustrating, in a simplified form, brain wavesynchrony over time in various sleep stages, including the onset of aseizure or unstable brain state, is shown according to an exemplaryembodiment. The seizure onset may be determined using other bodyparameters. During onset of a seizure or unstable brain state andwithout the CNS, instead of fluctuating in stage 2 sleep, the brainwaves in stage 2 sleep may become more synchronous relative to thesynchrony of the brain waves in stage 1 sleep, as indicated by a fifthsegment 412. After the seizure or unstable brain state, the synchrony ofthe brain increases as the patient transitions to an awake state, asindicated by a sixth segment 414. The patient then transitions from anawake state to stage 1 sleep and the synchrony of the brain waves mayincrease (i.e., become more synchronous) relative to the synchrony ofthe brain waves when the patient is awake, as indicated by the seventhsegment 416.

A medical device (e.g., the IMD 104 of FIG. 1) may monitor brain wavesynchrony level changes of the patient 102 based on the sleep cycleinformation (e.g., the EEG data) to adjust one or more CNS parameters.The one or more CNS parameters may include a pulse width, an outputcurrent, a CNS frequency, a CNS duty cycle, a CNS on-time, a CNSoff-time, a CNS frequency sweep, burst frequency, or a combinationthereof. The one or more CNS parameters may be adjusted such thatsynchrony of the brain waves may substantially conform to the synchronyprofile. For example, when the patient is in stage 2 sleep, the one ormore CNS parameters may be adjusted such that synchrony of the brainwaves may fluctuate (as in normal stage 2 sleep). As another example,when the patient is in stage 3 sleep, the one or more CNS parameters maybe adjusted such that the synchrony may decrease (driving the patienttoward REM stage sleep). One CNS parameter that may be used to affectthe synchrony of the brain is frequency of stimulation pulses. Forexample, higher frequency stimulation pulses (e.g., 100 Hz or more,100-200 Hz, 100-350 Hz) may have a desynchronizing affect while lowfrequency stimulation pulses (e.g., 30 Hz or less, 50 Hz or less, lessthan 100 Hz) may have a synchronizing effect. Therefore, low frequencystimulation pulses may be used to drive the patient from stage 1 sleepto stage 2 sleep and stage 2 sleep to stage 3 sleep while higherfrequency stimulation pulses may be used to drive the patient from stage3 sleep to REM stage sleep. As another example, the CNS may be vagusnerve stimulation (VNS) to stimulate the vagus nerve. Conventional VNS(e.g., pulse frequency of about 30 Hz, pulse width around 250-500microseconds, on-time of about 30 sec, and an off-time of 5 minutes) maybe used to drive the patient from stage 1 sleep to stage 2 sleep andstage 2 sleep to stage 3 sleep. Microburst VNS (e.g., pulse frequency ofabout 100-250 Hz, pulse width around 250-500 microseconds, 2-10 pulsesper burst, an interburst interval of about 100 milliseconds to 1 second,a burst duration of 100 milliseconds or less) may be used to drive thepatient from stage 3 sleep to REM stage sleep.

Referring to FIG. 5A, a diagram of a first sleep quota 500 of a patient(e.g., the patient 102 of FIG. 1) with a seizure disorder beforereceiving CNS therapy to treat the seizure disorder is shown accordingto an exemplary embodiment. The first sleep quota 500 may include afirst portion 502, a second portion 504, a third portion 506, and afourth portion 508. The first sleep quota 500 may be a sleep quota ofthe patient when the patient experiences seizures during sleep. Thefirst portion 502 may correspond to an accumulative amount of time thepatient spent in stage 1 sleep in a first sleep period (e.g., a night)before receiving the CNS therapy. The first sleep period may include oneor more sleep cycles. The second portion 504 may correspond to anaccumulative amount of time the patient spent in stage 2 sleep in thefirst sleep period. The third portion 506 may correspond to anaccumulative amount of time the patient spent in stage 3 sleep in thefirst sleep period. The fourth portion 508 may correspond to anaccumulative amount of time the patient spent in REM stage sleep in thefirst sleep period.

Referring to FIG. 5B, a diagram of a second sleep quota 510 of thepatient of FIG. 5A after receiving the CNS therapy to treat the seizuredisorder is shown according to an exemplary embodiment. The second sleepquota 510 may include a fifth portion 512, a sixth portion 514, aseventh portion 516, and an eighth portion 518. The fifth portion 512may correspond to an accumulative amount of time the patient spent instage 1 sleep in a second sleep period (e.g., a night) during the CNStherapy or after the CNS therapy (while recovering). The second sleepperiod may include multiple sleep cycles. The sixth portion 514 maycorrespond to an accumulative amount of time the patient spent in stage2 sleep in the second sleep period. The third portion 506 may correspondto an accumulative amount of time the patient spent in stage 3 sleep inthe second sleep period. The fourth portion 508 may correspond to anaccumulative amount of time the patient spent in REM stage sleep in thesecond sleep period.

Information regarding efficacy of the CNS therapy may be determinedbased on a comparison of the first sleep quota 500 to the second sleepquota 510 (e.g., via the IMD 104 of FIG. 1). A result of the comparisonmay indicate that the seventh portion 516 is greater than the thirdportion 506 and the eighth portion 518 is greater than the fourthportion 508. Thus, the comparison may indicate that the patient spendsmore time in stage 3 sleep and REM stage sleep during or after the CNStherapy. The increase of time the patient spends in stage 3 sleep andREM stage sleep may indicate that the CNS is effective in treating aparticular disorder. For example, when the CNS therapy is to treat oneor more seizure disorders, the comparison may indicate that the CNStherapy is effective in treating the seizure orders. In a particularembodiment, the first sleep quota 500 and/or the second sleep quota 510may be compared to a threshold to determine a degree of efficacy. Forexample, a threshold of REM stage sleep may correspond to a particularamount of time that a healthy person spends in REM stage sleep in asleep cycle and/or a sleep period. The fourth portion 508 and the eighthportion 518 may be compared to the threshold to determine an amount ofimprovement (e.g., how much more time the patient spends in REM stagesleep) as a measure of the efficacy.

The information regarding efficacy of the CNS therapy and/or the degreeof efficacy may be determined by the IMD 104 of FIG. 1, the sensor datacollection system 106, the external programming device 108, the externalcomputing device 160, or a combination thereof. The IMD 104, the sensordata collection system 106, the external programming device 108, theexternal computing device 160, or a combination thereof, may generate arecommendation (e.g., via a report) regarding adjustments that can bemade to improve the efficacy based on the information regarding efficacyof the CNS therapy and/or the degree of efficacy.

FIG. 8 is a flow chart of a third particular embodiment of a method ofoperation of a medical device to treat seizures during sleep. The method800 includes receiving body parameter data of a patient, at 802. Forexample, referring to FIG. 1, the IMD 104 may receive body parameterdata of the patient 102. The method 800 also includes determining thatthe patient is in a particular sleep cycle stage based on the bodyparameter data, at 804. For example, referring to FIG. 1, the IMD 104may determine that the patient 102 is in a particular sleep cycle stage.As an illustrative non-limiting example, the IMD 104 may determine thatthe patient is in stage 2 sleep. The method 800 further includesdetecting, while the patient is in the particular sleep cycle stage, aseizure event based on a synchrony of brain waves of the patient, at806. For example, as shown at 412 of FIG. 4, an onset of a seizure eventmay be detected while the patient is in stage 2 sleep. The method 800includes adjusting a cranial nerve stimulation parameter tosubstantially conform the brain waves of the patient to a targetsynchrony profile associated with the particular sleep cycle stage, at808. For example, referring to FIG. 4, a cranial nerve stimulationparameter may be adjusted to increase synchrony of the brain waves ofthe patient to substantially conform the brain waves to the stage 2segment 406.

The IMD 104, the sensor data collection system 106, the externalprogramming device 108, the external computing device 160, or acombination thereof, may communicate the information regarding efficacyof the CNS therapy and/or the degree of efficacy to the patient, to ahealth care provider, or a combination thereof. For example, the IMD104, the sensor data collection system 106, the external programmingdevice 108, the external computing device 160, or a combination thereof,may generate a report that includes the information regarding theefficacy of the CNS therapy and/or the degree of efficacy, may show theinformation regarding efficacy of the CNS therapy and/or the degree ofefficacy via a display, etc. The IMD 104, the sensor data collectionsystem 106, the external programming device 108, the external computingdevice 160, or a combination thereof, may adjust one or more CNSparameters based on the information regarding the efficacy of the CNStherapy and/or the degree of efficacy.

Referring to FIG. 6, a flow chart of a method 600 of operation of amedical device, such as the IMD 104 of FIG. 1, the sensor datacollection system 106, the external programming device 108, the externalcomputing device 160, or a combination thereof, associated with acranial nerve stimulation therapy to treat seizures during sleep isshown according to an exemplary embodiment. The method 600 includesdetermining sleep cycle information related to a sleep cycle of apatient based on body parameter data, at 602. For example, referring toFIG. 1, based on the body parameter data, the IMD 104 may determinesleep cycle information related to a sleep cycle of the patient 102. Themethod 600 may also include adjusting a cranial stimulation parameterbased on the sleep cycle information, at 604. For example, referring toFIG. 1, based on the sleep cycle information, the IMD 104 may adjust oneor more CNS parameters to adjust the CNS applied to the patient 102. Theone or more CNS parameters may include a pulse width, an output current,a CNS frequency, a CNS duty cycle, a particular nerve or nervesstimulated, a CNS frequency sweep, a CNS on-time, a CNS off-time, a CNSburst stimulation, or a combination thereof. As another example,referring to FIG. 4, the IMD 104 may also, or in the alternative, affecta synchrony of brain waves by adjusting the one or more CNS parametersto drive the patient through each stage of a sleep cycle, or from onesleep stage to another, to reduce seizure onsets based on the sleepcycle information.

In a particular embodiment, the method 600 further includes evaluatingthe sleep cycle information to determine a particular sleep stage, at606. For example, referring to FIG. 1, the IMD 104, the sensor datacollection system 106, the external programming device 108, the externalcomputing device 160, or a combination thereof, may evaluate the sleepcycle information to determine a sleep stage of the patient. In aparticular embodiment, the method 600 further includes evaluating thesleep cycle information to detect a sleep stage transition, at 608. Forexample, referring to FIG. 1, the IMD 104, the sensor data collectionsystem 106, the external programming device 108, the external computingdevice 160, or a combination thereof, may evaluate the sleep cycleinformation to detect a sleep stage transition.

In a particular embodiment, the method 600 further includes evaluatingthe sleep cycle information to determine an amount of time the patientspends in one or more sleep stages during a particular sleep cycle, at610. For example, referring to FIG. 1, the IMD 104, the sensor datacollection system 106, the external programming device 108, the externalcomputing device 160, or a combination thereof, may evaluate the sleepcycle information to determine an amount of time the patient 102 spendsin one or more sleep stages during a particular sleep cycle. In aparticular embodiment, the method 600 further includes evaluating thesleep cycle information to determine an amount of time the patientspends in one or more sleep stages during a sleep period that includesmultiple sleep cycles, at 612. For example, referring to FIG. 1, the IMD104, the sensor data collection system 106, the external programmingdevice 108, the external computing device 160, or a combination thereof,may evaluate the sleep cycle information to an amount of time thepatient 102 spends in one or more sleep stages during a sleep periodthat includes multiple sleep cycles.

Thus, the method 600 may enable a medical device to gather and evaluatepatient information through each stage of a sleep cycle. Completing asleep cycle may improve sleep quality of the patient and may reduceseizure onsets.

Referring again to FIG. 6, a flow chart of a method 620 of operation ofa medical device, such as the IMD 104 of FIG. 1, associated with acranial nerve stimulation therapy is shown according to an exemplaryembodiment. The method 620 includes determining a sleep stage or sleepstage transition of a patient based on body parameter data, at 622. Forexample, referring to FIG. 1, based on the body parameter data, the IMD104 may determine a sleep stage or sleep stage transition of the patient102. The method 620 may also include adjusting a cranial stimulationparameter, at 624. The adjustment may be made for a variety of reasonsdepending on the patients sleep architecture. For example, referring toFIGS. 1 and 6, the IMD 104 may adjust the CNS parameter such that theCNS may drive the patient 102 toward deep sleep (e.g., stage 3 sleep)when the patient: begins to transition from a light sleep stage (e.g.,stage 2 sleep) to an awake state, at 630; transitions from stage 1 sleepto stage 2 sleep, at 632; is in a light sleep stage (e.g., stage 2sleep), at 634; has been in a light sleep state (e.g., stage 2 sleep)for a predetermined amount of time 636; or a combination thereof. Afterthe cranial nerve stimulation parameter is adjusted, the method 620 mayfurther include stimulating a cranial nerve (e.g., vagus nerve,trigeminal nerve, hypoglossal nerve, glossopharyngeal nerve, or acombination thereof) with the adjusted parameter to move the patienttoward a deep sleep stage (e.g., stage 3 sleep), at 626. In the deepsleep stage (e.g., sleep stage 3), the method 620 may further includeadjusting a cranial nerve stimulation parameter, at 628, and stimulatingthe cranial nerve with the adjusted cranial nerve stimulation parameterto move the patient toward a REM stage, at 630. The synchrony of brainwaves may be affected by adjusting the one or more CNS parameters todrive the patient from light sleep to deep sleep and from deep sleep toREM. Driving the patient in and/or through the sleep stages may improvethe patient's sleep architecture and neurologic condition. For example,applying CNS with parameters adjusted based on sleep cycle informationmay reduce the number of seizures or unstable brain states the patientexperiences during sleep. In addition, improved sleep quality may reducethe number of seizures or unstable brain states during periods in whichthe patient is awake.

FIG. 7 is a flow chart of a second particular embodiment of a method ofoperation of a medical device, such as the IMD 104 of FIG. 1, the sensordata collection system 106, the external programming device 108, theexternal computing device 160, or a combination thereof, associated witha cranial nerve stimulation therapy to treat seizures during sleepaccording to an exemplary embodiment. The method 700 includesdetermining sleep cycle information related to a sleep cycle of apatient based on body parameter data, at 702. For example, referring toFIG. 1, based on the body parameter data, the IMD 104 may determinesleep cycle information related to a sleep cycle of the patient 102. Themethod 700 also includes evaluating the sleep cycle information todetermine information regarding efficacy of a cranial nerve stimulationtherapy, at 704. For example, referring to FIG. 5, the informationregarding efficacy of the CNS therapy may be determined based on acomparison of the first sleep quota 500 to the second sleep quota 510.The method 700 further includes generating a report that includes theinformation regarding efficacy, at 706. For example, referring to FIG.5, the IMD 104, the sensor data collection system 106, the externalprogramming device 108, the external computing device 160, or acombination thereof, may generate a report that includes informationregarding efficacy of the CNS therapy and/or the degree of efficacy.Thus, the method 700 may enable determination of information regardingefficacy of a therapy. Determining efficacy of a therapy may enableadjustment of the therapy to improve the efficacy.

Although the description above contains many specificities, thesespecificities are utilized to illustrate some of the exemplaryembodiments of this disclosure and should not be construed as limitingthe scope of the disclosure. The scope of this disclosure should bedetermined by the claims, their legal equivalents. A method or devicedoes not have to address each and every problem to be encompassed by thepresent disclosure. All structural, chemical and functional equivalentsto the elements of the disclosure that are known to those of ordinaryskill in the art are expressly incorporated herein by reference and areintended to be encompassed by the present claims. A reference to anelement in the singular is not intended to mean one and only one, unlessexplicitly so stated, but rather it should be construed to mean at leastone. No claim element herein is to be construed under the provisions of35 U.S.C. §112, sixth paragraph, unless the element is expressly recitedusing the phrase “means for.” Furthermore, no element, component ormethod step in the present disclosure is intended to be dedicated to thepublic, regardless of whether the element, component or method step isexplicitly recited in the claims.

The disclosure is described above with reference to drawings. Thesedrawings illustrate certain details of specific embodiments thatimplement the systems and methods of the present disclosure. However,describing the disclosure with drawings should not be construed asimposing on the disclosure any limitations that may be present in thedrawings. The present disclosure contemplates methods, systems andprogram products on any machine-readable media for accomplishing itsoperations. The embodiments of the present disclosure may be implementedusing an existing computer processor, or by a special purpose computerprocessor incorporated for this or another purpose or by a hardwiredsystem.

As noted above, embodiments within the scope of the present disclosureinclude program products comprising computer readable storage device, ormachine-readable media for carrying, or having machine-executableinstructions or data structures stored thereon. Such machine-readablemedia can be any available media which can be accessed by a generalpurpose or special purpose computer or other machine with a processor.By way of example, such machine-readable media can comprise RAM, ROM,EPROM, EEPROM, CD ROM or other optical disk storage, magnetic diskstorage or other magnetic storage devices, or any other medium which canbe used to carry or store desired program code in the form ofmachine-executable instructions or data structures and which can beaccessed by a general purpose or special purpose computer or othermachine with a processor. The disclosure may be utilized in anon-transitory media. Combinations of the above are also included withinthe scope of machine-readable media. Machine-executable instructionscomprise, for example, instructions and data which cause a generalpurpose computer, special purpose computer, or special purposeprocessing machines to perform a certain function or group of functions.

Embodiments of the disclosure are described in the general context ofmethod steps which may be implemented in one embodiment by a programproduct including machine-executable instructions, such as program code,for example, in the form of program modules executed by machines innetworked environments. Generally, program modules include routines,programs, objects, components, data structures, etc., that performparticular tasks or implement particular abstract data types.Machine-executable instructions, associated data structures, and modulesrepresent examples of program code for executing steps of the methodsdisclosed herein. The particular sequence of such executableinstructions or associated data structures represent examples ofcorresponding acts for implementing the functions described in suchsteps.

Embodiments of the present disclosure may be practiced in a networkedenvironment using logical connections to one or more remote computershaving processors. Logical connections may include a local area network(LAN) and a wide area network (WAN) that are presented here by way ofexample and not limitation. Such networking environments are commonplacein office-wide or enterprise-wide computer networks, intranets and theInternet and may use a wide variety of different communicationprotocols. Those skilled in the art will appreciate that such networkcomputing environments will typically encompass many types of computersystem configurations, including personal computers, hand-held devices,multi-processor systems, microprocessor-based or programmable consumerelectronics, network PCs, servers, minicomputers, mainframe computers,and the like. Embodiments of the disclosure may also be practiced indistributed computing environments where tasks are performed by localand remote processing devices that are linked (either by hardwiredlinks, wireless links, or by a combination of hardwired or wirelesslinks) through a communications network. In a distributed computingenvironment, program modules may be located in both local and remotememory storage devices.

An exemplary system for implementing the overall system or portions ofthe disclosure might include a general purpose computing device in theform of a computer, including a processing unit, a system memory, and asystem bus that couples various system components including the systemmemory to the processing unit. The system memory may include read onlymemory (ROM) and random access memory (RAM). The computer may alsoinclude a magnetic hard disk drive for reading from and writing to amagnetic hard disk, a magnetic disk drive for reading from or writing toa removable magnetic disk, and an optical disk drive for reading from orwriting to a removable optical disk such as a CD ROM or other opticalmedia. The drives and their associated machine-readable media providenonvolatile storage of machine-executable instructions, data structures,program modules, and other data for the computer.

It should be noted that although the flowcharts provided herein show aspecific order of method steps, it is understood that the order of thesesteps may differ from what is depicted. Also two or more steps may beperformed concurrently or with partial concurrence. Such variation willdepend on the software and hardware systems chosen and on designerchoice. It is understood that all such variations are within the scopeof the disclosure. Likewise, software and web implementations of thepresent disclosure could be accomplished with standard programmingtechniques with rule based logic and other logic to accomplish thevarious database searching steps, correlation steps, comparison stepsand decision steps. It should also be noted that the word “component” asused herein and in the claims is intended to encompass implementationsusing one or more lines of software code, and/or hardwareimplementations, and/or equipment for receiving manual inputs.

The foregoing descriptions of embodiments of the disclosure have beenpresented for purposes of illustration and description. It is notintended to be exhaustive or to limit the disclosure to the precise formdisclosed, and modifications and variations are possible in light of theabove teachings or may be acquired from practice of the disclosure. Theembodiments were chosen and described in order to explain the principalsof the disclosure and its practical application to enable one skilled inthe art to utilize the disclosure in various embodiments and withvarious modifications as are suited to the particular use contemplated.

The illustrations of the embodiments described herein are intended toprovide a general understanding of the structure of the variousembodiments. The illustrations are not intended to serve as a completedescription of all of the elements and features of apparatus and systemsthat utilize the structures or methods described herein. Many otherembodiments may be apparent to those of skill in the art upon reviewingthe disclosure. Other embodiments may be utilized and derived from thedisclosure, such that structural and logical substitutions and changesmay be made without departing from the scope of the disclosure. Forexample, method steps may be performed in a different order than isshown in the figures or one or more method steps may be omitted.Accordingly, the disclosure and the figures are to be regarded asillustrative rather than restrictive.

Moreover, although specific embodiments have been illustrated anddescribed herein, it should be appreciated that any subsequentarrangement designed to achieve the same or similar results may besubstituted for the specific embodiments shown. This disclosure isintended to cover any and all subsequent adaptations or variations ofvarious embodiments. Combinations of the above embodiments, and otherembodiments not specifically described herein, will be apparent to thoseof skill in the art upon reviewing the description.

The Abstract of the Disclosure is submitted with the understanding thatit will not be used to interpret or limit the scope or meaning of theclaims. In addition, in the foregoing Detailed Description, variousfeatures may be grouped together or described in a single embodiment forthe purpose of streamlining the disclosure. This disclosure is not to beinterpreted as reflecting an intention that the claimed embodimentsrequire more features than are expressly recited in each claim. Rather,as the following claims reflect, the claimed subject matter may bedirected to less than all of the features of any of the disclosedembodiments.

What is claimed is:
 1. A method comprising: receiving, at a computingdevice, body parameter data of a patient; determining that the patientis in a particular sleep cycle stage based on the body parameter dataand at least one of: detection of a sleep stage transition; an amount oftime the patient spends in one or more stages during the particularsleep cycle; an amount of time the patient spends in one or more stagesduring a sleep period that includes multiple sleep cycles; and acombination thereof; detecting, while the patient is in the particularpreselected sleep cycle stage, a seizure event; and adjusting, at thecomputing device, a cranial nerve stimulation parameter.
 2. The methodof claim 1, wherein the body parameter data compriseselectroencephalography (EEG) data, electrooculography (EOG) data,electromyography (EMG) data, electrocardiography (ECG) data,accelerometer data, or a combination thereof.
 3. The method of claim 1,wherein the body parameter data is received from a sensor that isattached to the patient.
 4. The method of claim 1, further comprisingreadjusting the cranial nerve stimulation parameter in association witha first transition from a light sleep stage to an awake state; a secondtransition from stage 1 sleep to stage 2 sleep; the patient being in thelight sleep stage; the patient being in the light sleep stage for aparticular amount of time; or a combination thereof.
 5. The method ofclaim 4, further comprising stimulating a cranial nerve based on thereadjusted cranial nerve stimulation parameter to drive the patienttoward a deep sleep stage.
 6. The method of claim 1, wherein the time instage three sleep is less than a predetermined threshold.
 7. The methodof claim 1, further comprising applying stimulation signals to a vagusnerve or a trigeminal nerve of the patient via a therapy delivery unitbased on the adjusted cranial nerve stimulation parameter.
 8. The methodof claim 1, wherein the cranial nerve stimulation parameter indicates apulse width, an output current, a cranial nerve stimulation frequency, acranial nerve stimulation duty cycle, a particular nerve or nervesstimulated, a cranial nerve stimulation frequency sweep, a cranial nervestimulation on-time, a cranial nerve stimulation off-time, or acombination thereof.
 9. The method of claim 1, further comprising:initiating application of first cranial nerve stimulation, based on afirst value of the cranial nerve stimulation parameter, to the patientto drive the patient from the particular sleep cycle stage to a nextsleep cycle stage; after initiating application of the first cranialnerve stimulation, determining based on the body parameter data that thepatient remains in the particular sleep cycle stage; and initiatingapplication of second cranial nerve stimulation, based on a second valueof the cranial nerve stimulation parameter, to the patient to drive thepatient from the particular sleep cycle stage to the next sleep cyclestage.
 10. The method of claim 1, wherein the seizure event correspondsto an epileptic seizure.
 11. A method comprising: receiving, at acomputing device, body parameter data of a patient; determining that thepatient is in a particular sleep cycle stage based on the body parameterdata; detecting, while the patient is in the particular sleep cyclestage, an event; initiating application of a first cranial nervestimulation based on a first value of a cranial nerve stimulationparameter to drive the patient from the particular sleep cycle stage toa next sleep cycle stage; after initiating application of the firstcranial nerve stimulation, determining based on the body parameter datathat the patient remains in the particular sleep cycle stage; andinitiating application of a second cranial nerve stimulation based on asecond value of the cranial nerve stimulation parameter to drive thepatient from the particular sleep cycle stage to the next sleep cyclestage.
 12. The method of claim 11, wherein the event corresponds to anepileptic seizure.
 13. The method of claim 11, wherein the eventindicates a transition from stage two sleep toward wakefulness.
 14. Themethod of claim 11, wherein the event indicates time in a REM sleepstage that is less than a threshold and the next sleep cycle stagecorresponds to the REM sleep stage.
 15. The method of claim 11, whereinthe body parameter data comprises electroencephalography (EEG) data,electrooculography (EOG) data, electromyography (EMG) data,electrocardiography (ECG) data, accelerometer data, or a combinationthereof.
 16. The method of claim 11, wherein the body parameter data isreceived from a sensor that is attached to the patient.
 17. The methodof claim 11, further comprising applying stimulation signals to a vagusnerve or a trigeminal nerve of the patient via a therapy delivery unitbased on the adjusted cranial nerve stimulation parameter.
 18. Themethod of claim 11, wherein the cranial nerve stimulation parameterindicates a pulse width, an output current, a cranial nerve stimulationfrequency, a cranial nerve stimulation duty cycle, a particular nerve ornerves stimulated, a cranial nerve stimulation frequency sweep, acranial nerve stimulation on-time, a cranial nerve stimulation off-time,or a combination thereof.
 19. A method comprising: applying a firstelectrical signal to a cranial nerve of a patient to treat a medicalcondition, wherein the first electrical signal is defined by a firstvalue of at least one of a current amplitude, a pulse width, afrequency, an ON time and an OFF time; receiving, at a computing device,body parameter data of a patient selected from at least one ofelectroencephalography (EEG) data, electrooculography (EOG) data,electromyography (EMG) data, electrocardiography (ECG) data, andaccelerometer data; determining that the patient is in a particularsleep cycle stage based on the body parameter data; adjusting the firstvalue to a second value to obtain a second electrical signal, whereinsaid second value is selected to drive the patient from the particularsleep cycle stage to a next sleep cycle stage; and applying the secondelectrical signal to said cranial nerve of the patient.
 20. The methodof claim 19, wherein the particular sleep stage is a light sleep stage,and wherein said second value is selected to drive the patient from saidlight sleep stage to a deep sleep stage.
 21. The method of claim 19,wherein the particular sleep stage is selected from stage one sleep,stage 2 sleep, stage 3 sleep, and stage 4 sleep.
 22. A methodcomprising: applying a first electrical signal to a cranial nerve of apatient to treat a medical condition, wherein the first electricalsignal is defined by a first value of at least one of a currentamplitude, a pulse width, a frequency, an ON time and an OFF time;receiving, at a computing device, body parameter data of a patientselected from at least one of electroencephalography (EEG) data,electrooculography (EOG) data, electromyography (EMG) data,electrocardiography (ECG) data, and accelerometer data; determining thatthe patient is in a particular sleep cycle stage based on the bodyparameter data; detecting an event associated with the medical conditionwhile the patient is in the particular sleep cycle stage; adjusting thefirst value to a second value to obtain a second electrical signal,wherein said second value is selected based at least in part on theparticular sleep cycle stage; and applying the second electrical signalto said cranial nerve of the patient.